His birth year and early life are unclear (accounts differ). He was long said to have risen alone from oil seller to lord of Mino, but today the view that father and son rose over two generations prevails.
Around this time he gained power as a retainer of the Toki, military governors of Mino, taking over the names of the Nagai and Saitō families.
Around this time he drove his lord Toki Yorinari out of Mino and took real power (date debated). A model of gekokujō, the low overthrowing the high, he was called "the Viper of Mino".
Making peace with Oda Nobuhide of Owari, he married his daughter Kichō (Nōhime) to Nobuhide's son Nobunaga (year debated).
He met his son-in-law Nobunaga at Shōtoku-ji in Owari. Nobunaga, rumoured a fool, appeared in formal dress, and Dōsan was reportedly impressed by his calibre.
He passed headship to his son Yoshitatsu and took the tonsure as Dōsan, but relations with Yoshitatsu later soured.
Yoshitatsu killed his younger brothers, Dōsan's favourites, making the rift between father and son irreparable.
At the Battle of Nagaragawa he fought his son Yoshitatsu's large army and was killed. Before dying he reportedly wrote a letter bequeathing Mino to Nobunaga.
Hachisuka MasakatsuAkechi MitsuhideOda NobunagaHori Hidemasa
Hōjō Sōun (Ise Sōzui)Amago TsunehisaHojo UjitsunaTaigen SessaiMōri MotonariFrancis XavierŌuchi YoshitakaMatsunaga Hisahide
People of the Sengoku/Azuchi-Momoyama period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.